Dr. Claudio Modini, head of the hospital emergency room, said Gandolfini arrived at the hospital at 10:40 p.m. and was pronounced dead after resuscitation efforts in the ambulance and hospital failed.

An autopsy would be performed starting 24 hours after the death, as required by law, he told The Associated Press.

The actor, known for his portrayal of the tortured Italian-American mob boss Tony Soprano was to have given a special class at the Taormina Film Festival, an annual festival that takes place against the backdrop of Taormina's spectacular Roman amphitheater. Actor Jeremy Irons gave a similar class earlier in the week.

Gandolfini was to have been given the "Taormina City Prize" on Saturday before attending the festival's closing ceremony alongside actress Marisa Tomei.

Festival organizers Mario Sesti and Tiziana Rocca said instead they would organize a tribute "to celebrate his great achievement and talent." They said they had heard from Gandolfini a few hours before he died and "he was very happy to receive this award and be able to travel to Italy."

The U.S. Embassy in Rome, which said it had learned about the death from the media, said it would be available to provide a death certificate and help prepare the body for return to the United States. The embassy said it can often take between four and seven days to arrange for it to be sent outside of Italy.

The embassy spokesman declined further comment, directing inquiries to the family.

It isn't yet known yet what caused his heart to stop beating. Sudden cardiac arrest can be due to a heart attack, a heart rhythm problem, or as a result of trauma. The chance of cardiac arrest increases as people get older; men over age 45 have a greater risk. Men in general are up to three times more likely to have a sudden cardiac arrest than women.